When pipes are employed in situations where movement may be experienced between components of a piping system, the piping system needs to be designed to accommodate such movement, in order to avoid excess stress, strain, or bending moment, which may result in premature failure of the piping system. In one application, namely the collection of gas from sanitary landfills, the normally used plastic pipe products, such as high density polyethylene (HDPE), is subject to stress and strain from subsidence of the landfill mass below the surface of the landfill. Settlement, as well as temperature fluctuations, make design of piping systems for such applications problematic. The challenge of providing a safe, fluid tight, and sanitary environment for collection of gas from a landfill, has continued to require development of new apparatus and methods, especially to take advantage of bio-gas and route the same to an apparatus which can productively utilized such gas for the generation of heat and/or electrical or mechanical power. Currently, there is a great but as yet unmet need for systems that can easily accommodate telescoping of a pipe joint as the unstable landfill moves and settles, whether along a pipeline run or below a wellhead. Additionally, slip joints suitable for such a job could also find application for other utility applications, such as water or sewer pipe, or electrical conduit, where actual elongation or contraction is expected in normal operation and must be accommodated, or in applications where the potential for such movement must be included in the equipment installed, for example in connections between buildings and earthquake resistant/tolerant foundations. Consequently, this disclosure provides description of a novel slip coupling apparatus for pipe joints, and describes novel methods of employing such slip joints, such as in gas gathering piping in sanitary landfill applications.
The foregoing figures, being merely exemplary, contain various elements that may be present or omitted from actual implementations and various configurations of a slip coupling which may be used for a variety of pipe joint situations, depending upon the circumstances. An attempt has been made to draw the figures in a way that illustrates at least those elements that are significant for an understanding of the various embodiments and aspects of the invention. However, various other elements of the unique slip coupling are also shown and briefly described to enable the reader to understand how various features, including optional or alternate features, may be utilized in order to provide a simple slip coupling for piping systems.